1. Field of the Invention
The present invention relates to a developing device provided in image forming apparatuses such as a facsimile machine, a copying machine, and a printer, and an image forming apparatus provided with the developing device.
2. Description of the Related Art
As an example of the developing device described above, there has been a known developing device in which a magnetic roller is further arranged to oppose a developing roller which is arranged to oppose an image bearing member (for example, a photoconductive drum), and magnetic poles having magnetic polarities different from one another are provided in the developing roller and the magnetic roller so as to improve a binding force of a magnetic brush formed between the developing roller and the magnetic roller (for example, refer to Japanese Patent Unexamined Publication No. 2005-274924).
However, while the image forming apparatus provided with the developing device can improve an ability of collecting toners on the developing roller, the binding force of the magnetic brush causes a developer to accumulate in a periphery between the developing roller and the magnetic roller. Such accumulation disadvantageously causes the developer to blow out of the developing device to contaminate inside of the image forming apparatus or causes so-called carrier adherence such as adherence of the developer to a surface of the image bearing member.